Fig. 1. Comparison of mechanical properties in four alloys. Engineering stress-strain curves for the CrCoNi-3W alloy (orange curve), CrCoNi alloy (red curve), Ni-3W (blue curve) and Ni (navy curve). All curves except Ni-3W are redrawn from data of ref. [29] [28], and [8]. GS: grain size.

Fig. 2. Comparison dislocation structures in three alloys. TEM images showing the dislocation structures for (a) CrCoNi-3W; (b) CrCoNi. The red lines in (b) represent the extended dislocation; (c) CrCoNi-3W. The extended dislocation is indicated by orange lines with the nanoscale segment detrapping marked by orange arrows. All TEM images were taken under beam axis [110].

Fig. 3. In-situ TEM observation of dislocation movement in CrCoNi-3W MEA and Ni-3W alloy. TEM images taken during in-situ straining experiments in (a) CrCoNi-3W alloy (snapshot from Supplementary Movie 1). The magnified TEM images on the top right corner are an exemplificative dislocation named “dislocation line 1”, marked by red arrows. (b) TEM images taken during in-situ TEM straining experiment in Ni-3W alloy (snapshot from Supplementary Movie 2). The yellow and green arrows are indicated the typical dislocation named “dislocation line 2” and “dislocation line 2’”, respectively.

Fig. 4. Comparison of microstructure under the similar amount of (～5 %) strain in three alloys counterparts. (a) CrCoNi-3W, (b) Ni-3W and (c) CrCoNi. All the TEM images were taken under beam axis [110].

Fig. 5. Comparison of the dislocation core structure. (a) CrCoNi-3W, (b) Ni-3W and (c) CrCoNi. All HAADF image taken with the <110> zone axis, showing the atomic structure of full dislocation, with the Burgers vector b of $\frac{1}{2}$ [110].

Fig. 6. Atomic scale elemental mapping and corresponding line profiles of atomic fraction of individual elements taken from respective EDS maps in three alloys. (a) Ni-3W; (b) CrCoNi-3W. The white circles are indicated a Ni-rich or Ni-poor region in Ni maps; and (c) CrCoNi. Each group of images above contains an atomic resolution HAADF image, corresponding EDS maps of all constituent elements and a representative line profile of atomic fraction taken from the EDS maps.

Fig. 7. Comparison of atomic scale strain distribution. (a) CrCoNi-3W; (b) CrCoNi; (c) Ni-3W. Every group of images includes HAADF image and corresponding maps of horizontal normal strain (εxx), vertical normal strain (εyy) and shear strain (εxy).